43, no asthma, don't smoke. get bronchitis every time i get a cold now, 3 times in 1 yr. why is this happening, & how can i prevent this?

See an allergist: you may be having chronic upper airways inflammation, rhinos infusoria, for whatever reason that's affecting your lower airways, bronchitis. An Allergist / Immunologist evaluation will help decipher your trigger factors, whether you have allergic vs non allergic inflammation and puts a plan of treatment. Check aaaai.org or acaai.org for an allergist in your area, good luck